The coinventors named on this application are also coinventors on other related applications generally relating to butterfly valves (including Ser. Nos 374,897 filed 30 June 1989; and 395,234, filed 17 Aug. 1989; 422,210, filed 16 Oct. 1989; 422,380, filed 16 Oct. 1989; 422,487, filed 16 Oct. 1989; 426,921, filed 4 Oct. 1989; and 451,659, filed 15 Dec. 1989, all cofiled or copending with the present application, and all assigned to Allied-Signal, Inc.
The present invention relates generally to valve apparatus and methods. More particularly, the present invention relates to butterfly valve apparatus and methods wherein a duct defines a flow path for conveying a flow of fluid. A plate-like valve member is pivotally disposed in the duct about a transverse axis, and is conformal at its outer periphery to the internal wall shape of the duct. The valve member is pivotal between a first position transverse to the flow path and substantially sealingly engaging the duct wall to close fluid flow therein, and a second position spanning the flow path generally parallel therewith to allow and control the fluid flow therein.
A conventional butterfly valve is set forth by U.S. Pat. No. 3,971,414, issued 27 July 1976 to H. Illing. The '414 patent also discusses the general state of the butterfly valve art prior to the invention by Illing. According to the teaching of the '414 patent, the actuating torque required to rotate the valve member of a butterfly valve from its closed position to an open position may be reduced by utilizing an articulated valve member That is, the plate-like butterfly valve member includes a leading wing and a trailing wing with respect to fluid flow The leading wing of Illing's valve member is defined in part by a servo tab or spoiler tab which is carried by and pivotally movable relative to the remainder of the valve member By pivoting the spoiler tab ahead of the valve member in the opening direction so as to point into the fluid flow, Illing changes the angulation and effective movement arm of the fluid pressure and flow forces on the spoiler tab. Illing hopes to reduce the total torque opposing opening of the valve member in comparison to previously known butterfly valves. The articulation of the spoiler tab is such that it pivots from an aligned position to move ahead of the valve member during most of the pivotal movement of the latter in the opening direction. During the last portion of the pivotal movement of the valve member to its fully open position, the servo tab reverses its relative pivotal movement and returns to an aligned position achieved when the valve member is fully open. In this way, the valve member and servo tab align with one another and with the fluid flow in the fully open position of the valve member.
A reduction in the operating torque required to move the valve member from its closed to its open position, such as assertedly achieved by the invention of Illing, has been a long-recognized need in the field of butterfly valves. Unfortunately, the invention of Illing as set forth in the '414 patent does not fully comprehend the usual design requirements for a butterfly valve, and has not enjoyed commercial acceptance, to the Applicants' knowledge.
It will be understood by those skilled in the pertinent art that the valve member of a conventional butterfly valve must ordinarily achieve a sealing tight fit with the walls of the duct. Ordinarily the plate-like butterfly valve member carries a seal member at the outer periphery thereof. This seal member, for example, a piston ring type, o-ring, or lip seal, is resiliently and sealingly engageable with the duct wall in the closed position of the valve member. Thus, it is conventional for the plate-like valve member to be circumferentially continuous, and to be skewed slightly relative to the pivot shaft supporting the valve member. That is, the periphery of the valve member is disposed upstream of the shaft on one side and down stream of the shaft on the other to allow use of a circumferentially continuous sealing member at the periphery of the valve member. The pivot shaft may transect the duct perpendicularly to the flow path, or be angulated relative to the latter. The valve taught by the '414 patent does not permit use of a circumferentially continuous sealing member on the valve member periphery.
In view of the deficiencies of the known butterfly valve art it is an object for this invention to reduce or eliminate the opposing torque which must be overcome to move the valve member of a butterfly valve from its closed to its open position.
Desirably, fluid pressure and flow forces acting on the plate-like butterfly valve member may be used to reduce or eliminate the opposing torque, or to effect pivotal movement of the valve member.
Still further, in view of the deficiencies of the valve taught by Illing in the '414 patent, it is desirable to be able to use a circumferentially continuous sealing member on the butterfly valve member.
Accordingly the present invention provides a duct, a plate-like butterfly valve member pivotally disposed in said duct and carried by a shaft member journally on the latter and extending externally thereof to receive valve actuating torque, and means for relatively translating said valve member and shaft member along an action line generally perpendicular to the latter in response to rotation of said shaft member.
Accordingly the present invention provides a duct, a plate-like butterfly valve member pivotally disposed in said duct and carried by a shaft member journaled on the latter and extending externally thereof to receive valve actuating torque, and means for relatively translating said valve member and shaft member along an action line generally perpendicular to the latter in response to relative rotation therebetween.
An advantage of the present invention is that it allows use of a circumferentially continuous sealing member on the plate-like valve member of the butterfly valve.